Page 3 of 5 of the Sweet Corn Guide

Companion Plants for Sweet Corn

Author: Greg Baka

Besides being a favorite food among people, corn is super tasty to several pests. Corn also needs certain nutrients for optimal growth. This article explains how including beneficial plants in and around your corn patch can deter pests and provide better corn yields.

Simply put, companion planting is the practice of growing beneficial plants (friends) alongside each other to glean the complementary characteristics of the other. This includes nutritional needs, growth behaviors or propensity to repel pests.

Nitrogen Fixing

Sweet corn needs a plentiful and steady supply of nitrogen for the best yield. If you’re thinking nitrogen is a gas, you are right. And if you’re wondering how a gas can get into your corn plants, then read on.

nitrogen nodules on roots Image Credit

Some plants have bacteria that live on them. Those bacteria convert nitrogen gas into nitrogen that is trapped in bacteria in the soil and on certain plants, known as "nitrogen fixing" plants. When you plant these nitrogen-fixing plants on your sweet corn plot, you will help provide your corn with the nitrogen it needs for healthy growth.

Legumes, which are a member of the pea family, are excellent nitrogen fixers. Well-known legumes include alfalfa, clover, peas, chickpeas, lentils, lupin bean, mesquite, carob, soybeans, peanuts and tamarind. Cool-weather varieties can be planted as a cover crop in fall, storing up nitrogen all winter, and then tilled into the soil in early spring ahead of corn-planting time. Warm-weather beans can be planted with the corn, as explained below.

A list of nitrogen-fixing plants is available here.

Legumes (Beans) and Nitrogen

Legumes use bacteria called Rhizobium bacteria of which there are multiple varieties. To be sure your legumes are adding as much nitrogen as possible, contact your local extension agent to determine the Rhizobium bacteria variety that goes with the legumes you’re planting. The agent can tell you where to get it so you can put the bacteria starter directly on the seeds to ensure the bacteria is there when you plant.

Corn and Beans

Most home gardeners, however, simply plant beans with their corn to fix nitrogen by absorbing it from the air or pulling it out of the ground. Any bean will work – bush, pole, wax, green, yellow, purple, string, flat, soy, Lima, runner, mottled, etc. The possibilities are endless.

The "Three Sisters" Method

Three sisters planting method Image Credit

A traditional example of companion planting is the Three Sisters group—corn, pole beans and winter squash—grown together for their complementary natures: the tall corn supports the climbing beans; the squash shades the ground with big, scratchy leaves to inhibit weeds and pests; and the fast-growing beans provide nitrogen.

Bush beans can be planted along with the corn, alternating rows or mixing beans and corn throughout the rows. With pole beans, however, the corn needs time to grow before the bean vines start to climb the stalk. Plant pole beans when the corn is 4 to 6 inches high, putting four bean seeds 1 inch deep in each corn hill, spacing them 3 inches from the corn plants. Water thoroughly and keep soil evenly moist until bean seedlings emerge in seven to 10 days. As the bean runners form, train them to grow up the corn stalks.

Other Three Sisters Planting Methods

Prepare the soil by adding fish scraps, well-rotted manure, compost or wood ash to increase fertility, if desired. Soak the corn seeds for four or five hours to speed germination. Below are two different layouts for planting the threesome. Either way, the corn is always planted first, followed by the beans and lastly the squash. Remember, too, that corn is pollinated by wind, so plant your corn in one area of the garden.

  • Small mounds - in mounds of about 18” inches in diameter, sow five to seven corn seeds evenly spaced in each mound, 1 to 1 1/2 inches deep. Water the mounds regularly so the soil remains constantly moist. Sow the pole bean seeds when the corn plants are about 6 inches tall. Push four or five bean seeds 1 inch deep, evenly spaced around the corn plants. At every seventh mound, sow two bean seeds only. Sow four or five squash seeds in the seventh mounds at the same time as the pole beans or after the pole beans have sprouted, evenly spaced around the corn plants and 1 inch deep. This seed distribution provides squash plants that ramble over all the mounds and suppress weeds.
  • Small mound planting method Image Credit
  • Large mounds - for a larger circle, make a mound of soil about a foot high and four feet wide. When the danger of frost has passed, plant the corn in the center of the mound. Sow six kernels of corn an inch deep and about ten inches apart in a circle of about 2 feet in diameter. When the corn is about 5 inches tall, plant four bean seeds, evenly spaced, around each stalk. About a week later, plant six squash seeds, evenly spaced, around the perimeter of the mound.

Other Possible Benefits

Planting pole beans has the added benefit of helping to anchor the corn plants, keeping them from falling over, a problem called “lodging”. If lodging is a problem in your garden, here is a good article that explains the conditions that make this phenomenon most likely.

Note that there are mixed reviews as to the success of pole beans preventing lodging, with some accounts of the beans overtaking the corn. As with all gardening techniques, our advice is to experiment with different varieties of beans to learn which ones work best with your sweet corn, soil, climate and taste buds.

Fertilizing a Three Sisters Plot

The Old Farmer’s Almanac recommends fertilizing the three sisters combo the first year as the nitrogen in pole bean root nodules becomes available to corn and squash only the second year after planting. Fertilize with a high-nitrogen fertilizer, such as a 12-4-8 ready-to-use, slow-release, granular product. Spread the granules at a rate of 4 tablespoons per 4 square feet when the pole beans and squash plants are 4 inches tall or apply according to the manufacturer's instructions. Alternatively, use an organic fertilizer, such as a 3-inch layer of well-rotted manure. Spread the manure around the plants, avoiding their stems. This manure layer also will help suppress weeds until the squash plants are growing strongly.

Other Companion Plants

Other plants also go well with corn, such as:

Plant thyme to repel earworm Image Credit
  • Vines - Vine plants provide shade to keep the roots of the corn plants moist and also serve as a natural weed suppressant. Similar to squash, cucumber vines grow well near corn. The vines can also help deter raccoons.
  • Melons - are in the same family as squash and cucumbers and can be used in place of winter squash in a 3 sister’s arrangement. The long vines will offer the same protection and living mulch as squash does.
  • Peas - are another legume that fixes nitrogen in the soil, making it a perfect corn companion plant. Peas are planted as early as possible in spring, while corn is not planted until the soil is warm. Plant corn seeds directly in the pea patch to glean their nitrogen and save space.
  • Dill - is a great herb to grow near corn. It can improve flavor of the corn and it will attract beneficial insects such as lady bugs and parasitic wasps.
  • Marigolds and Nasturtiums - These two flowers are must in all gardens because of their ability to repel or trap pests. They repel aphids, including corn aphids and other pests, as well as attracting beneficial bugs.
  • Annual flowers - are often overlooked in a vegetable garden, but they are more than just beautiful. Flowers will attract beneficial insects such a green lacewings and parasitic wasps, which will help your plants fight against pests. Cosmos and zinnias are two easy-to-grow examples.
  • Borage - can help repel worms that attack corn plants. Borage also attracts beneficial insects such as lady bugs to you garden.
  • Summer Savory - is another herb that helps repel pests and attract beneficial bugs.
  • Thyme - helps repel the corn earworm.
  • Aromatic Plants - such as lavender, mint, oregano, dill, garlic, marigolds, basil and sage help deter deer.

What NOT to Plant with Corn

Below are plants that should be planted in another area of the garden from corn:

  • Tomatoes - share common enemies with corn. Grown near each other, they will attract both the corn earworm and the tomato hornworm. Also both corn and tomatoes are heavy feeders and will compete for nutrients in the soil.
  • Brassicas - All members of the cabbage family including broccoli, Brussels sprouts, kale, cauliflower should be planted apart from corn. Corn shades the brassicas too much, stunting their growth. As well as both crops are also heavy feeders and will compete for nutrients in the soil.

Plants to Repel Animals

To Keep Raccoons Out of the Corn in Your Garden

Raccoon corn damage Image Credit

Raccoons are said to have very sensitive feet and avoid walking on prickly plants. Some plants that have proven effective in keeping raccoons out of your sweet corn patch includes:

  • pumpkin
  • cucumbers
  • oriental poppies
  • globe thistle
  • Kentucky Wonder pole beans

All of these plants can be planted between your corn or in the rows.

Raccoons are also said to avoid very spicy foods as well as all plants in the tomato family. Plants like habanero chilies and tomatoes can be planted around the outside of your corn patch, but not too near the corn. The theory is that raccoons will try the easy-to-reach plants first, decide they are not good and not come back to try the stuff in the middle.

Plants with a strong odor, such as mint and garlic, are also claimed to successfully keep raccoons away.

Another suggestion is to plant a small crop of sweet corn away from the garden specifically for the wildlife to eat. Since it is closer to cover they will feel safer eating the corn there than crossing the open yard to get to your sweet corn patch.

There are ideas as well as commercial products such as the Nite-Guard that you may want to give a try if you have lots of raccoon problems. And here is another article with more ideas to keep out raccoons.

To Keep Deer out of the Corn in Your Garden

Deer corn damage Image Credit

If deer are hungry enough, they will eat almost any plant. High-calorie sweet corn is one of their favorites to help them bulk up to get them through winter. Deer have an amazing sense of smell and will avoid aromatic plants that interrupt their ability to smell predators. Surrounding your corn patch or your entire garden with very thick rows of lavender or marigolds may discourage deer from entering your garden.

One of the best determents for both deer and raccoon is simply to have a dog that is allowed to be in your garden area overnight.

Plants to Attract Good Bugs

Earworm Beetles are one of the most harmful insects to corn. No plant is known to repel them. However, there are plants that attract other insects like the green lacewings and the soldier beetles that keep can keep the earworm moth population under control.

The following plants will attract many beneficial insects to your garden and protect more than just your sweet corn. A variety of high-nectar plants will do the most good in your garden.

  • Achillea millefolium – yarrow
  • Ammi majus – laceflower
  • Anethum graveolens – dill
  • Angelica species – angelicathis
  • Baccharis species – baccharis
  • Shasta daisies attract beneficial insects
  • Boltonia asteroides – boltonia
  • Coreopsis species – tickseed
  • Cosmos bipinnatus – cosmos
  • Eriogonum species – native buckwheat
  • Eupatorium perfoliatum – common boneset
  • Helianthus annuus – sunflower
  • Leucanthemum x superbum – shasta daisy   Image Credit
  • Labularia maritima – sweet alyssum
  • Phacelia tanacetifolia – lacy phacelia
  • Pycnanthemum species – mountain mint
  • Ratibida pinnata – praire coneflower
  • Rudbeckia species – black-eyed Susans
  • Solidago species – goldenrod
  • Spirea alba – meadowsweet
  • Symphyotrichum species – hardy aster
  • Veronicastrum virginicum – Culver’s root
  • Zizia aurea – golden Alexanders
  • Zizia aptera – heartleaf Alexanders

List provided by Savvy Gardening.

Now that you know what to plant alongside your corn, in our next article we will tell you how to water, weed, and hill your crop.

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